Lower limb biomechanical differences in runners with long-duration and short-duration patellofemoral pain

To investigate the biomechanical alterations in the lower limbs of runners with varying durations of patellofemoral pain (PFP) and provide a basis for the rehabilitation treatment of PFP.

We recruited 14 recreational runners with PFP lasting more than 12 months (long-duration group), 12 runners with PFP lasting less than 3 months (short-duration group), and 16 runners without PFP (control group). Landmark coordinates and ground reaction forces during running were collected. One-way ANOVA was performed to compare the lower limb biomechanics among the groups.

Compared to the control group, the long-duration group demonstrated significantly greater peak knee external rotation angle (p = 0.010), knee abduction moment (p < 0.001), hip abduction moment (p = 0.007), and ankle external rotation moment (p = 0.004). The short-duration group showed significantly greater peak ankle eversion angle (p = 0.004) and ankle dorsiflexion-plantarflexion range of motion (p = 0.003) compared to the controls. No significant differences were found in peak vertical impact ground reaction forces (p = 0.906) or peak patellofemoral joint stress (p = 0.150) during the landing phase between runners with PFP and controls.

Runners with long-duration PFP exhibited greater external knee rotation angles, knee and hip abduction moments during running, while runners with shorter PFP duration showed greater ankle eversion. These findings support the need for duration-specific rehabilitation strategies tailored to the distinct biomechanical characteristics associated with PFP symptom duration.